[erlang-questions] beginner: mnesia secondary indices with ordered_set

Scott Lystig Fritchie <>
Wed Oct 31 04:20:58 CET 2007

>>>>> "uw" == Ulf Wiger <> writes:

uw> No, Mnesia has only one type of index.

Yes, and it's implemented by an ETS bag, which won't give you the
efficient prefix search that Paul's looking/hoping for.

uw> The rdbms contrib in
uw> Jungerl implements index tables a bit differently (as full mnesia
uw> tables), and supports ordered index, among other things.
uw> But to the best of my knowledge, rdbms is not actively used by
uw> anyone (unless Rudolph van Graan is still using it).

I had some deadline pressure and couldn't rework our app to use rdbms
whole-heartedly.  :-(  But, back then, I adapted the technique that
rdbms uses for secondary indexing, and it works very well.  Many
thanks to Ulf and Rudolph for their guidance and suggestions.


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